1. Technical Field
The present invention relates to an electro-optical device and an electronic apparatus, and, more particularly, to an electro-optical device having excellent electrostatic resistance.
2. Related Art
In, for example, the field of electro-optical device, such as an active matrix liquid crystal display device, breakage of a thin film transistor (hereafter referred to as ″TFT) may occur due to static electricity with which a substrate is charged during manufacturing. To prevent such an element breakage, the following technology has been proposed (refer to, for example, JP-A-11-95257). In this technology, short-circuit wires that electrically connect scanning lines and data lines to each other are formed on a substrate, and static electricity is spread towards the outer periphery of the substrate through the short-circuit wires to prevent sudden excess electrical current from flowing to the TFT.
In a liquid crystal display device, what is called a chip-on-glass (COG) mounting structure for mounting a driving integrated circuit (IC) directly onto a substrate is known. In recent years, there is a demand for size reduction of a liquid crystal display device including a driving circuit as a result of a reduction in size of an electronic apparatus, such as a cellular phone. Therefore, the COG mounting structure is considerably used. In a liquid crystal display device using such a COG mounting structure, an electricity removing pattern is formed at an end of an electrode or a wire pattern for protecting the electrode or the wire from static electricity (refer to, for example, JP-A-2001-92371).
However, a liquid crystal display device including the COG mounting structure is such that an external substrate, such as a flexible printed circuit (hereafter referred to as “FPC”), for supplying a power supply voltage or an image signal to the driving IC mounted on the substrate is connected between the liquid crystal display device and an electronic apparatus. This causes static electricity to enter the liquid crystal display device through the FPC, which may cause the following problems to occur at external connection terminals.
FIG. 10 is a plan view of a related liquid crystal display device. A plurality of external connection terminals 101 are provided at a peripheral end of a substrate 100. An FPC (not shown) is connected to the external connection terminals 101 at one end (upper end in FIG. 10). A wire 104 for connection to its associated terminal of a driving IC 102 is provided at the other end of each external connection terminal 101. A pad 103 is provided at an end of each wire 104. Usually, before shipment of a product, electrostatic resistance is measured, and a high voltage of a few kV corresponding to static electricity is forcefully applied to each external connection terminal 101 to inspect its breakage state. The inventors of the application made inspections and found out that, in the liquid crystal display device having the structure shown in FIG. 10, as the voltage is increased, breakage (wire breakage) occurs at ends of the wires 104 disposed closer to the driving IC 102. The inventors found out that, in particular, the breakage (wire breakage) tends to occur in bent portions (corresponding to portions surrounded by a dashed ellipse K in FIG. 10) of the wires 104 connected to the respective external connection terminals that are represented by reference numerals 101a to 101d. In other words, a margin with respect to a standard of electrostatic resistance inspection is small, in particular, at the external connection terminals 101a to 101d, giving rise to a problem in reliability.
Although JP-A-11-95257 and JP-A-2001-92371 disclose structures that protect, for example, devices, electrodes, and wires from static electricity, electrostatic breakage around the external connection terminals cannot be prevented from occurring. In addition, although, in the foregoing description, liquid crystal display devices are taken as examples, the aforementioned problems are not limited to liquid crystal display devices. That is, they are problems that are common to electro-optical devices having the aforementioned COG mounting structure.